Oxidative dehydrogenation process



' below about 350 C.

United States Patent O 3,308,192 OXIDATHV E DEHYDROGENATION PROCESSLaimonis Bajars, Princeton, N.J., assignor to Petro-Tex ChemicalCorporation, Houston, Tex., a corporation of Delaware No Drawing. FiledOct. 22, 1965, Ser. No. 502,494 14 Claims. (Cl. 260-680) Thisapplication is a continuation-in-part of my earlier filed pendingapplication Serial Number 250,020 filed January 8, 1963, entitled,Dehydrogenation Process, now abandoned, which in turn was acontinuation-inpart of my now abandoned applications Serial Number52,776 filed August 30, 1960, entitled, Improved DehydrogenationProcess, Serial Number 72,327 filed November 29, 1960, entitled,Dehydrogenation Process, Serial Number 145,992 filed October 18, 1961,entitled, Dehydrogenation of Hydrocarbons, Serial Number 145,993 filedOctober '18, 1961, entitled, Dehydrogenation Process, Serial Number156,953 filed December 4, 1961, entitled, Dehydrogenation Process,Serial Number 156,956 filed December 4, 1961, entitled, Dehydrogenation,Serial Number 196,870 filed May 23, 1962, entitled, DehydrogenationProcess, Serial Number 207,105 filed July 2, 1962, entitled, ImprovedDehydrogenation Process, and Serial Number 825,656 filed July 8, 1959,entitled, Dehydrogenation Process.

This invention relates to a process for dehydrogenating organiccompounds and relates more particularly to the dehydrogenation oforganic compounds in the vapor phase at elevated temperatures .in thepresence of oxygen, iodine and an improved inorganic cont-act mass.

It has been found recently that a great variety of dehydrogenatableorganic compounds may be dehydrogenated by reacting a mixture of anorganic compound containing at least one pair of adjacent carbon atoms,each of which possess at least one hydrogen atom, iodine, or aniodine-liberating material, and oxygen under specified conditions at anelevated temperature, and at a reduced partial pressure of the organiccompound, in the presence of certain metals or compounds thereof toobtain the corresponding unsaturated organic compound containing atleast one or CEC grouping.

I have found, quite unexpectedly, that this process may be improved sothat increased selectivities and yields of unsaturated organic compoundderivatives containing the or CEC grouping are obtained more efiicientlyeven with less iodine and under less stringent process conditions, e.g.at lower temperatures, when such reaction is conducted in the presenceof a contact mass comprising as a first component at least one elementof a metal of Groups Ia and Ila, (i.e. the alkali and alkaline earthmetals) together with a second component which is manganese or amanganese compound.

The process of this invention can be applied to a great variety oforganic compounds to obtain the corresponding unsaturated derivativethereof. Such compounds normally will contain from 2 to 20 carbon atoms,at least one H l l grouping, that is, adjacent carbon atoms eachcontaining at least one hydrogen atom and having a boiling point Suchcompounds may contain in 3,308,192 Patented Mar. 7, 1967 addition tocarbon and hydrogen, oxygen, halogens, nitrogen and sulphur. Among theclasses of organic compounds Which are dehydrogenated by means of thenovel process of this invention are .alkanes, alkenes, alkyl halides,ethers, esters, aldehydes, ketones, organic acids, alkyl aromaticcompounds, alkyl heterocyclic compounds, cyanoalkanes, cycloalkanes andthe like. Illustrative dehydrogenation include ethyl-benzene to styrene,isopropyl-benzene to a-methyl styrene, ethylcyclohexane to styrene,cyclohexane to benzene, ethane to ethylene and acetylene, ethylene toacetylene, propane to propylene, isobutane to isobutylene, n-butane tobutene and butadiene-1,3, butene-l to butadiene-1,3 and vinyl acetylene,cis or trans butent-2 to -butadiene-1,3, butane or butene to vinylacetylene, butadiene-l,3 to vinyl acetylene, methyl butene to isoprene,isobutane to isobutylene, propionaldehyde to acrolein, ethyl chloride tovinyl chloride, propionitrile to acrylonitrile, methyl isobutyrate tomethyl meth-acrylate, and the like. Other representative materials whichare readily dehydrogenated in the novel process of this inventioninclude ethyl toluene, the alkyl chlorobenzenes, ethyl naphthalene,isobutyronitrile, propyl chloride, isobutyl chloride, ethyl fluoride,ethyl dichloride, butyl chloride, the chlorofluoroethanes, methylethylketone, diethyl ketone, methyl propionate, and the like. This inventionis useful in the preparation of vinylidene compounds containing at leastone CH =C group, that is, a compound possessing at least one groupcontaining a terminal methylene group attached by a double bond to acarbon atom, and 2 to 12 carbon atoms and is particularly useful in thedehydrogenation of hydrocarbons containing 2 to 5 carbon atoms oraliphatic nitriles of 3 to 4 carbon atoms. Preferred compounds to bedehydrogenated are hydrocarbons of 4 to 8 carbon atoms having at leastfour contiguous non-quaternary carbon atoms. Aliphatic acyclichydrocarbons of from 4 to 5 or 6 carbon atoms are preferred.Theinvention is further particularly adapted to provide butadiene-1,3from butane and butene and isoprene from isopentane and isopentene inhigh yields and excellent conversion and selectivity.

As shown by the examples below and the disclosures herein, the novelprocess of this invention is applicable to a great variety of organiccompounds containing 2 to 20 carbon atoms and at least one pair ofadjacent carbon atoms bonded together and each carbon atom possessing atleast one hydrogen atom including the following: hydrocarbons includingboth alkanes and alkenes, especially those containing 2 to 6 or 8carbons; carbocyclic compounds containing 6 to 12 carbon atoms,including both alicyclic compounds and aromatic compounds of the formulawherein Ar is phenyl or naphthyl, R is hydrogen or methyl and X and Yare hydrogen or alkyl radicals containing 1 to 4 carbon atoms, orhalogen; alkyl ketones containing 4 to 6 carbon atoms; aliphaticaldehydes containing 3 to 6 carbon atoms; cyanoalkanes containing 2 to 6carbon atoms; halo-alkanes and halo-alkenes containing 2 to 6 carbonatoms, particularly chloroand fiuoro-alkanes and the like. Vinylidenecompounds containing the group, that is, containing a terminal methylenegroup attached by a double bond to a carbon atom, are

readily obtained from organic compounds containing 2 to 12 carbon atomsand at least one group wherein adjacent carbon atoms are singly bondedand possess at least one hydrogen each. For example, vinylidene halides;vinyl esters; acrylic acid and alkyland halo-acrylic acids and esters;vinyl aromatic compounds; vinyl ketones; vinyl heterocyclic comounds;diolefins containing 4 to 6 carbon atoms, olefins containing 2 to 8carbon atoms, and the like are obtained as products. The vinylidenecompounds normally contain from 2 to 12 carbon atoms and are well knownas a commercially useful class of materials for making valuable polymersand copolymers therefrom.

Useful feeds as starting materials may be mixed hydrocarbon streams suchas refinery streams. For example, the feed material may be theolefin-containing hydrocarbon mixture obtained as the product from thedehydrogenation of hydrocarbons. Another source of feed for the presentprocess is from refinery by-products. Although various mixtures ofhydrocarbons are useful, the preferred hydrocarbon feed contains atleast 50 weight percent butene-1, butene-2, n-butane and/orbutadiene-1,3 and mixtures thereof, and more preferably contains atleast 70 percent n-butane, butene-1, butene-2 and/or butadiene-1,3 andmixtures thereof. Any remainder usually will be aliphatic hydrocarbons.The process of this invention is particularly effective indehydrogenating acyclic aliphatic hydrocarbons to provide a hydrocarbonproduct wherein the major unsaturated product has the same number ofcarbon atoms as the feed hydrocarbon.

Iodine may be employed as free iodine or as any iodinecontainingmaterial which liberates the specified amount of free iodine under theconditions of reaction as defined hereinafter. For example, iodine,hydrogen iodide, the alkyl iodides, such as methyl iodide and ethyliodide, wherein the alkyl groups preferably contain 1 to 6 carbon atoms;ammonium iodide and the like. Additional iodine compounds areiodohydrins such as ethylene iodohydrin; iodo substituted aliphaticacids such as iodoacetic acid; organic amine iodide salts such as methylamine hydroi-odide; and other iodine compounds such as S1 S1 SOI 10 ICHIg, C1 and the like. Generally, the iodine compound will have aboiling or decomposition point of less than 400 C., and usually nogreater than 100 C. Preferred are ammonium iodide, molecular orelemental iodine and/or hydrogen iodide. It is an advantage of thisinvention that hydrogen iodide or ammonium iodide may be employed as theiodine source, with one advantage being that the hydrogen iodide orammonium iodide in the effluent from the reactor may be fed directlyback to contact the hydrocarbons in the dehydrogenation reactor withoutany necessity of converting the hydrogen iodide to iodine. It isunderstood that when a quantity of iodine is referred to herein, both inthe specification and the claims, that this refers to the calculatedquantity of iodine in all forms present in the vapor state under theconditions of reaction regardless of the initial source or the form inwhich the iodine is present. For example, a reference to 0.05 mol ofiodine would refer to the quantity of iodine present whether the iodinewas fed as 0.05 mol of I or 0.10 mol of H1.

The amount of iodine usually will be in an amount greater than about0.0001 mol of iodine, such as at least 0.001 mol, or the equivalentamount of iodine-liberating material per mol of organic compound to bedehydrogenated, more usually at least about 0.01 mol equivalent ofiodine per mol of organic compound will be employed. It is one of theunexpected advantages of this invention that only very small amounts ofiodine are required, such as up to 0.2 and normally less than about 0.2mol total equivalent of iodine and more desirably less than 0.1

mol of iodine per mol of organic compound to be dehydrogenated. Amountsof iodine between 0.001 or 0.005 and 0.08 or 0.09 mol of iodine per molof the organic compound to be dehydrogenated are preferred, with therange of about 0.001 to 0.05 being particularly preferred. Preferablythe iodine will be present in an amount no greater than 5 or 10 molpercent of the total feed to the dehydrogenation zone.

The amount of oxygen employed will be at least onefourth mol of oxygenper mol of organic compound to be dehydrogenated. Generally greater than0.25 mol of oxygen per mol of the organic compound will be used.Excellent yields of the desired unsaturated derivatives have beenobtained with amounts of oxygen from about 0.4 to about 1.5 mols ofoxygen per mol of organic cornpoun-d, and within the range of or about0.25 or 0.4 to 2 mols of oxygen per mol of organic compound economic,production and process considerations will dictate more exactly thenormal ratio of oxygen to be used. A preferred range for oxygen is from0.5 to 1.2 mols of oxygen per mol of compound to be dehydrogenated.Oxygen is supplied to the reaction system as pure oxygen, or as oxygendiluted with inert gases such as helium, carbon dioxide or as air andthe like. In relation to iodine, the amount of oxygen employed isgreater than one mol, as 1.25 of oxygen per atom of iodine present inthe reaction mixture, usually greater than about 1.5 mols of oxygen peratom of iodine. Usually the ratio of the mols of oxygen to the mols ofiodine will be at least 3 such as from 5 or 8 to 500 and preferably willbe between 15 and 300 mols of oxygen per mol of iodine.

While the total pressure on systems employing the process of thisinvention normally will be at or in excess of atmospheric pressure,vacuum may be used. Higher pressures, such as about or 200 p.s.i.g. maybe used. The partial pressure of the organic compound under reactionconditions usually will be equivalent to below 10 inches mercuryabsolute when the total pressure is atmospheric. Better results andhigher yields of desired product are normally obtained when the partialpressure of the organic compound is equivalent to less than aboutone-third or one-fifth of the total pressure. Also because the initialpartial pressure of the hydrocarbon to be dehydrogenated is generallyequivalent to less than about 10 inches of mercury at a total pressureof one atmosphere, the combined partial pressure of the hydrocarbon tobe dehydrogenated plus the dehydrogenated hydrocarbon will also beequivalent to less than about 10 inches of mercury. For example, underthese conditions, if butene is being dehydrogenated to butadiene, at notime will be combined partial pressure of the butene and butadiene begreater than equivalent to about 10 inches of mercury at a totalpressure of one atmosphere. Preferably the hydrocarbon to bedehydrogenated should be maintained at a partial pressure equivalent toless than one-third the total pressure, such as no greater than sixinches or no greater than four inches of mercury, at a total pressure ofone atmosphere. The desired pressure is obtained and maintained bytechniques including vacuum operations, or by using helium, organiccompounds, nitrogen, steam and the like, or by a combination of thesemethods. Steam is particularly advantageous and it is surprising thatthe desired reactions to produce high yields of product are effected inthe presence of large amounts of steam. Steam is particularlyadvantageous to obtain the required low partial pressure of the organiccompound in the process. When steam is employed, the ratio of steam toorganic compound is normally above about two mols of steam permol oforganic compound such as within the range of about 2 or 5 to 20 or 30mols, although larger amounts of steam as high as 40 mols have beenemployed. The degree of dilution of the reactants with steam and thelike is related to maintaining the partial pressure of the organiccompound in the system at below about one-third atmosphere andpreferably below 10 inches mercury absolute when the total pressure onthe system is one atmosphere. For example, in a mixture of one mol ofbutene, three mols of steam and one mol of oxygen under a total pressureof one atmosphere the butene would have an absolute pressure ofone-fifth of the total pressure, or roughly six inches of mercuryabsolute pressure. Equivalent to this six inches of mercury buteneabsolute pressure at atmospheric pressure would be butene mixed withoxygen and iodine under a vacuum such that the partial pressure of thebutene is six inches of mercury absolute. A combination of a diluentsuch as steam together with a vacuum may be utilized to achieve thedesired partial pressure of the hydrocarbon. For the purpose of thisinvention, also equivalent to the six inches of mercury butene absolutepressure at atmospheric pressure would be the same mixture of one mol ofbutene, three mols of steam and one mol of oxygen under a total pressuregreater than atmospheric, for example, a total pressure of 15 or 20inches mercury above atmospheric. Thus, when the total pressure on thereaction zone is greater than one atmosphere, the absolute values forthe pressure of butene will be increased in direct proportion to theincrease in total pressure above one atmosphere. Another feature of thisinvention is that the combined partial pressure of the hydrocarbon to bedehydrogenated plus the iodine-liberating material will preferably alsobe equivalent to less than l0 inches of mercury, and preferably lessthan 6 or 4 inches of mercury, at a total pressure of one atmosphere.The lower limit of organic compound partial pressure will be dictated bycommercial considerations and normally will be greater than about 0.1inch of mercury absolute.

The temperature of the reaction is from above 400 C. to about 800 C. or1000 C. Preferably the temperatures will be from at least 450 C. to 900C., and generally will be at least about 500 C. The optimum temperaturemay be determined as by thermocouple at the maximum temperature of thereaction. Usually the temperature of reaction will be controlled betweenabout 450 C. and about 750 C. or 800 C.

The flow rates of the gaseous reactants may be varied quite widely andgood results have been obtained with organic compound gaseous flow ratesranging from about 0.25 to about 3 liquid volumes of organic compoundper volume of reactor packing per hour, the residence or contacttime ofthe reactions in the reaction zone under any given set of reactionconditions depending upon the factors involved in the reaction.Generally, the flow rates will be within the range of about 0.10 to 25or higher liquid volumes of the hydrocarbon to be dehydrogenated,calculated at standard conditions of 0 C. and 760 mm. of mercury pervolume of reactor space containing catalyst per hour (referred to aseither LHSV or liquid v./v./hr.). Usually the LHSV will be between 0.15and 15. The volume of reactor containing catalyst is that volume ofreactor space including the volume displaced by the catalyst. Forexample, if a reactor has a particular volume of cubic feet of voidspace, when that void space is filled with catalyst particles theoriginal void space is the volume of reactor containing catalyst for thepurpose of calculating the flow rates. The residence or contact time ofthe reactants in the reaction zone under any given set of reactionconditions depends upon all the factors involved in the reaction.Contact times ranging from about 0.01 to about two seconds at about 450C. to 750 C. have been used. A wider range of residence times may beemployed, as 0.001 second to about 10 or seconds. Residence time is thecalculated dwell time of the reaction mixture in the reaction zoneassuming the mols of product mixture are equivalent to the mols of feedmixture.

For conducting the reaction, a variety of reactor types may be employed.Fixed bed reactors may be used and fluid and moving bed systems areadvantageously applied to the process of this invention. In any of thereactors suitable means for heat removal may be provided. Tubu- 0 larreactors of large diameter which are loaded or packed with the solidcontact mass are satisfactory.

Good results have been obtained when the exposed surface of the solidcontact mass is greater than about 25 square feet, preferably greaterthan about 50 square feet per cubic foot of reactor as 75 or or higher.Of course, the amount of catalyst surface may be much greater whenirregular surface catalysts are used. When the catalyst is in the formof particles, either supported or unsupported, the amount of catalystsurface may be expressed in terms of the surface area per unit weight ofany particular volume of catalyst particles. The ratio of catalyticsurface to weight will be dependent upon various factors including theparticle size, particle distribution, apparent bulk density of thecarrier, and so forth. Typical values for the surface to weight ratioare such about /2 to 200 square meters per gram, although higher andlower values may be used.

Excellent results have been obtained by packing the reactor withcatalyst particles as the method of introducing the catalytic surface.The size of the catalyst particles may vary widely but generally themaximum particles size will at least pass through a Tyler StandardScreen which has an opening of 2 inches, and generally the largestparticles of catalyst will pass through a Tyler Screen with one inchopenings. Thus, the particle size when particles are usedpreferably willbe from about 10 microns to a particle size which will pass through aTyler Screen with openings of 2 inches. If a carrier is used thecatalyst may be deposited on the carrier by methods known in the artsuch as by preparing an aqueous solution or dispersion of the catalyst,mixing the carrier with the solution or dispersion until the activeingredients are coated on the carrier. The coated particles may then bedried, for example, in an oven at about C. Various other methods ofcatalyst preparation known to those skilled in the art may be used. Veryuseful carriers are the Alundums, silicon carbide, the Carborundums,pumice, kieselguhr, asbestos, and the like. When carriers are used, theamount of catalyst composition on the carrier will generally be in therange of about 2 to 80 weight percent of the total weight of the activecatalytic material plus carrier. Another method for introducing therequired surface is to utilize as a reactor a small diameter tubewherein the tube Wall is catalytic or is coated with catalytic material.If the tube wall is the only source of catalyst generally the tube willbe of an internal diameter of no greater than one inch such as less thaninch in diameter or preferably will be no greater than about /2 inch indiameter. The technique of utilizing fluid beds lends itself well to theprocess of this invention.

In the above descriptions of catalyst compositions, the compositiondescribed is that of the surface which is exposed in the dehydrogenationzone to the reactants. That is, if a catalyst carrier is used, thecomposition described as the catalyst refers to the composition of thesurface and not to the total composition of the surface coating pluscarrier. The catalytic compositions are intimate combinations ormixtures of the ingredients. These ingredients may or may not be presentas alloys. Catalyst binding agents or fillers may be used, but thesewill not ordinarily exceed about 50 percent or 65 percent by weight ofthe catalytic surface. The defined catalytic components will be the mainactive constituents in the catalyst and the catalyst may consistessentially of the defined catalytic components. The weight percent ofthe defined catalytic atoms will generally be at least 20 percent, andare preferably at least 35 percent of the composition of the catalystsurface exposed to the reaction gases and will generally be at least 51or about 80 atomic weight percent As measured by the Innes nitro enabsorption m th d on a representative unit volume of catalyst particles.The Innes 12116;??? is reported in Innes, W. B., Anal. Chem., 23, 759

of any cations in the surface, such as at least 80 atomic percent of anymetal cations in the surface.

The defined catalyst combinations may be employed in any form, e.g., aspellets, tablets, as coatings on carriers or supports, and the like, inboth fixed and fluidized beds. Other methods of catalyst preparationknown to those skilled in the art may also be used.

According to this invention, the catalyst is autoregenerative and thusthe process is continuous. Little or no energy input is required for theprocess and it may be operated essentially adiabatically. Moreover,small amounts of tars and polymers are formed as compared to prior artprocesses. It is also an advantage of this invention that triple bondcontaining compounds are more easily obtained than with catalystscontaining only one of the de fined components.

In the examples given below the conversions, selectivities and yieldsare expressed as mol percent based on the mols of the compound to bedehydrogenated fed to the reactor. The temperature of reaction listed isapproximately the maximum temperature in the reactor. The catalysts arepresent as fixed beds.

The Group Ia and Ha compounds used include, for example, oxides,hydroxides and salts such as the phosphates, sulfates, halides and thelike. Useful compound include, for example, lithium chloride, lithiumoxide, lithium bromide, lithium fluoride, lithium phosphate, sodiumhydroxide, sodium oxide, sodium chloride, sodium sulfate, berylliumoxide, sodium bromide, sodium iodide, sodium phosphate, sodium fluoride,potassium chloride, potassium bromide, potassium sulfate, potassiumiodide, potassium nitrate, potassium citrate, potassium hydroxide,potassium oxide, potassium phosphate, rubidium chloride, rubidiumbromide, rubidium iodide, rubidium oxide, magnesium acetate, magnesiumbromide, magnesium oxide, magnesium iodide, calcium oxide, calciumacetate, calcium oxalate, calcium chloride, calcium bromide, calciumiodide, calcium phosphate, calcium fluoride, strontium oxide, strontiumhydroxide, strontium chloride, strontium bromide, barium oxide, bariumchloride, barium hydroxide, barium sulfate, barium bromide, bariumiodide, beryllium chloride, and the like, and mixtures thereof.Preferred Group Ia and Ha metal elements are lithium, sodium, magnesium,potassium, calcium, strontium and barium, such as the oxides,phosphates, iodides, bromides, chlorides or fluorides of these metals.The oxides and halides and mixtures thereof are particularly preferred.Many of the Group Ia and 11a compounds may change during the preparationof the catalyst, during heating in a reactor prior to use in the processof this invention, or are converted to another form under the describedreaction conditions, but such materials still function as an effectivecompound in the defined process. For example, the halides may beconverted to the oxides or vice versa under the conditions of reaction.The amount of Group Ia metal compound or Group I la metal compound withthe additional metal or inorganic compound thereof may be varied quitewidely and while small amounts, as low one-tenth percent based on thetotal catalyst, have been used, much larger amounts may be employed inconcentrations up to where the Group In or IIa metal compound ispresent, such as up to 50 weight percent. Normally up to, or less than,50 percent, and more usually about one to about twenty-five percent ofthe Group Ia or Group Ha compound, such as about one to ten percent,with the remainder being the defined second inorganic metal compound, issatisfactory. On an atomic basis, the combined amount of the metal atomsof Group Ia and/or Ila will be from at least about 0.001 atom per atomof the defined second catalyst component and mixtures thereof. Excellentresults are obtained at ratios of about 0.01 to 1.0 or 1.5 atoms ofGroup Ia and Ila per atom of the elements from the second specifiedgroup, such as from orabout 0.01 to 0.02 to 0.5 atom of Group la and Ilaper atom of the elements from the second specified group.

Manganese or a variety of manganese compounds may be used as the secondcomponent in conjunction with the Group Ia and Ila metal compounds.Metals of the described second component group in elemental form may beemployed and are included within the scope of this invention. The metalsgenerally are changed to inorganic compounds thereof, at least on thesurface, under the reaction conditions set forth herein. Particularlyeffective are inorganic compounds such as the oxides and salts includingthe prosphates and the halides, such as the iodides, bromides, chloridesand fluorides. Inorganic compounds which are useful as the secondcomponent in the compounded contact mass for the process of thisinvention include manganese oxide, manganese phosphate, manganese,managanous chloride, and the like. Preferably the catalyst will be solidunder the conditions of reaction. Many of the salts, oxides andbydroxides of manganese may change during the preparation of thecatalyst, during heating in the reactor in the process of thisinvention, but such materials still function as an effective compound inthe defined process. For example, manganese nitrates or carbonates oracetates may be converted to the corresponding oxide or iodide under thereaction conditions defined herein. Salts which are stable or partiallystable at the defined reaction temperatures are likewise effective underthe conditions of the described reaction, as well as such compoundswhich are converted to another form in the reactor. rate, the catalystsare effective if the defined catalysts are present in a catalytic amountin contact with the reaction gases. Useful catalyst combinations includemanganese dioxide and lithium chloride, manganese phosphate and lithiumchloride or lithium hydroxide, manganese oxide together with lithiumbromide and potassium hydroxide, manganese chloride and potassiumchloride, manganese chloride and lithium chloride, and the like.

In Examples 1 to 5, a tubular one inch diameter Vycor 2 reactor, filledwith the described solid contact masses, equipped with an externalelectric furnace was used. The reaction conditions and the activematerials used are set forth in the specific examples. The organiccompound and oxygen were added at the top of the reactor; the hydrogeniodide solution was added to this stream as it entered the reactor andsteam Was added separately opposite this stream. The results arereported as mol percent conversion, selectivity and yield of desiredunsaturated product per pass.

Example 1 A contact mass was prepared by depositing a water slurrycontaining manganese oxide and 2.6 percent lithium chloride, calculatedon the manganese oxide, on inch AMC 3 granules by evaporation. Thecoated pellets were dried and placed in the one-inch diameter reactor toa depth of eight inches. Butene was dehydrogenated over this contactmass at a temperature of 1115 F. The molar ratio of reactants passedover this contact mass was one mol of butene at a flow rate of one LHSV,liquid hourly space velocity, 0.025 mol of I supplied as a percentsolution of ammonium iodide in water, 0.65 mol of oxygen supplied asair, and 13 mols of steam. A yield of 85.7 percent butadiene-1,3 perpass was obtained at a conversion of 87.2 percent and selectivity of98.3 percent.

Example 2 A similar contact mass to that of Example 1 containingmanganese oxide and percent lithium chloride was pre- 2 Vycor is thetrade name of Corning Glass Works, Corning, N.Y., and is composed ofapproximately 96 percent silica with the remainder being essentiallyB203.

3 Supplied by The Carboruntlum Company, type AMC pellets are polysurfacepellets of fused aluminum oxide characterized as having medium porosity(-50 percent), coarse grain and 300350 micron pore size.

At any 5 pared in the same way and evaluated under the same reactionconditions. Butadiene-1,3 was obtained in a yield of 85.1 percent at aconversion of 86.4 percent and selectivity of 98.5 percent. At 1196 F.,the yield of butadiene-1,3 was 97.9 percent per pass; at 1240 F., theyield of butadiene per pass was 91 percent.

Example 3 For comparison purposes with Examples 1 and 2, a contact massprepared from manganese oxide alone on AMC granules was evaluated and at1202 F., butene was dehydrogenated to butadiene-1,3 in a yield of 75percent at a conversion of 82 and selectivity of 91.5 percent.

When Example 1 above is repeated at 650 C. with a 95 percent manganeseoxidepercent lithium chloride contact mass, deposited on 4 to 6 meshfused alumina pellets with 0.05 mol of I as aqueous hydrogen iodide(hydroiodic acid), mols of steam and 0.85 mol of oxygen per mol oforganic compound being dehydrogenated, isobutylene is obtained fromisobutane, acrylonitrile from propionitrile, acrolein frompropionaldehyde, isoprene from 2-methyl butene-2, styrene fromethylbenzene, vinyl chloride from ethyl chloride, ethylene from ethane,styrene from ethylcyclohexane, methyl isopropenyl ketone from methylisopropyl ketone in good yields.

When the examples above are repeated with other contact masses such asmixtures of 95% manganese chloride and 5% calcium chloride, manganeseoxide and sodium chloride, 97.5% manganese phosphate and 2.5% rubidiumchloride or 2.5% K 00 good yields of butadiene-1,3 are obtained frombutene1.

Example 4 A mixture of 99 percent manganese oxide and 1 percent lithiumnitrate was deposited on 4 to 8 mesh Alundum pellets from water byevaporation. The dried coated pellets were placed in a reactor andheated to convert the lithium nitrate to lithium oxide. Butene-2 wasdehydrogenated over this contact mass at a liquid hourly space velocity(Ll-ISV) of butene of one, and a molar ratio of reactants of 1 mol ofbutene-Z, 0.025 mol of I added as a 25 percent aqueous solution ofammonium iodide, 0.65 mol of oxygen added as air and 13 mols of steam.At 1188 F., the butene-2 was dehydrogenated to butadiene-1,3 at a yieldof 87.2 percent, conversion of 93.1 percent and selectivity of 93.7percent.

Example 5 Using another contact mass consisting solely of manganeseoxide deposited on AMC granules and under the same reaction conditionsused in Example 4 and molar ration of reactants at 1202 F., a yield of75 percent butadicnc-l,3 was obtained at a conversion of 82 percent andselectivity of 91.5 percent.

The process of this invention is particularly applicable to thedehydrogenation of hydrocarbons, including dehydroisomerization anddehydrocyclization, to form a variety of acyclic compounds,cycloaliphatic compounds, aromatic compounds, and mixtures thereof. Forexample, 2-ethylhexene-1 may be converted to a mixture of aromaticcompounds such as toluene, ethyl benzene, p-xylene, o-xylene andstyrene.

I claim:

1. The method for dehydrogenating hydrocarbon compounds having 2 to 20carbon atoms to produce a dehydrogenated product having the same numberof carbon atoms and the same structure with the exception of the removedhydrogen atoms which comprises heating in the vapor phase at atemperature of above 400 C. a hydrocarbon compound having a a Trademarkfor alumina carriers.

group with oxygen in a molar ratio of greater than onefourth mol ofoxygen per mol of said hydrocarbon compound, iodine in an amount of lessthan about 0.2 mol of iodine per mol of said hydrocarbon compound, theratio of the mols of said oxygen to the mols of said iodine being atleast 2.5, the partial pressure of said hydrocarbon compound beingequivalent to less than one-half the total pressure in the presence of acatalyst comprising" as its main active constituent (1) a compoundselected from the group consisting of oxides, salts and hydroxides ofalkali and alkaline earth metals and mixtures thereof, and (2) manganeseor a manganese compound. I

2. The method of claim 1 wherein the said compound is a hydrocarbonhaving from 2 to 12 carbon atoms.

3. The method of claim 1 wherein the said compound is an acyclicaliphatic hydrocarbon of 4 to 6 carbon atoms.

4. The method of claim 1 wherein the said compound is a hydrocarbonselected from the group consisting of n-butene, n-butane, isopentene,isopentane and mixtures thereof.

5. The method of claim 4 wherein the said temperature is at least 450 C.

6. The method of claim 4 wherein steam is employed in the said vaporphase in an amount of from 2 to 30 mols of steam per mol of saidhydrocarbon.

7. The method of claim 4 wherein the oxygen is present in an amount ofgreater than 3.0 mols of oxygen per mol of said hydrocarbon and the saidiodine is present in an amount of from .001 to 0.09 mol of iodine permol of said hydrocarbon.

8. The method of claim 4 wherein the alkali and alkaline earth metalcompounds are present in an atfiount of from about .01 to 0.5 atom ofthe alkali or alkaline earth metal elements per atom of the metalelements of the said (2).

9. The method of claim 4 wherein the iodine is present in an amount ofno greater than 10 mol percent of the total gaseous mixture in thedehydrogenation zone.-

10. A method for dehydrogenating hydrocarbons con-- taining 4 to 5carbon atoms which comprises reacting in the vapor phase at atemperature between 400 C. and about 750 C. an aliphatic hydrocarboncontaining 4 to 5 carbon atoms with oxygen in a molar ratio of about 0.4mol to about 2 mols of oxygen per mol of hydrocarbon, and above 0.001mol to less than 0.2 mol per mol of aliphatic hydrocarbon of iodine, ata partial pressure of said hydrocarbon of less than about one-third thetotal pressure in the presence of a mixture of (1) a compound selectedfrom the group consisting of alkali metal oxides, alkaline metalhydroxides, alkaline earth metal oxides and alkaline earth metalhydroxides, and (2) manganese or an inorganic manganese compound.

11. The method of claim 1 wherein the said (1) is selected from thegroup consisting of lithium, sodium, magnesium, potassium, calcium,strontium, barium, and mixtures thereof.

12. The method of claim 1 wherein the said (1) and (2) are present asoxides, halides or mixtures thereof.

13. The method of claim 11 wherein the said 1) is a lithium compound.

14. The method of claim 11 wherein the said (1) is a calcium compound.

References Cited by the Examiner UNITED STATES PATENTS 3,106,590 10/1963Bittner 260-680 DELBERT E. GANTZ, Primary Examiner.

G. E. SCHMITKONS, Assistant Examiner.

1. THE METHOD FOR DEHYDROGENATING HYDROCARBON COMPOUNDS HAVING 2 TO 20CARBON ATOMS TO PRODUCE A DEHYDROGENATED PRODUCT HAVING THE SAME NUMBEROF CARBON ATOMS AND THE SAME STRUCTURE WITH THE EXCEPTION OF THE REMOVEDHYDROGEN ATOMS WHICH COMPRISES HEATING IN THE VAPOR PHASE AT ATEMPERATURE OF ABOVE 400*C. A HYDROCARBON COMPOUND HAVING A